User Agent and Assistive Technology Support Notes

Description

The purpose of this technique is to show how purely decorative images
in PDF documents can be marked so that they can be ignored by Assistive
Technology by using the /Artifact tag. This is typically accomplished
by using a tool for authoring PDF.

In PDF, artifacts are generally graphics objects or other markings
that are not part of the authored content. Examples of artifacts include
page header or footer information, lines or other graphics separating
sections of the page, or decorative images.

Example 2: Marking an image as an artifact in a PDF document using
an /Artifact tag or property list

The PDF specification allows images to be marked as "artifacts" as
defined in Section 14.8.2.2 (Real Content and Artifacts) in PDF
1.7 (ISO 32000-1). An artifact is explicitly distinguished from
real content by enclosing it in a marked-content sequence with the
/Artifact tag.

/Artifact

BMC ... EMC

or

/Artifact propertyList

BDC ... EMC

The first is used to identify a generic artifact; the second is
used for artifacts that have an associated property list. Note, to
aid in text reflow, artifacts should be defined with property lists
whenever possible. Artifacts lacking a specified bounding box are
likely to be discarded during reflow.

Resources

Tests

Procedure

For an image that is purely decorative, use one of the following
to verify that it is marked as an artifact:

Read the PDF document with a screen reader, listening to hear
that the decorative image is not announced when
reading the content line-by-line.

Using a PDF editor, make sure the decorative image is marked as an artifact.

Reflow the document and make sure the
decorative image does not appear on the page.

Use a tool that is capable of showing the /Artifact entry
or property list, such as aDesigner, to open the PDF document
and verify that decorative images are marked as artifacts.

Use a tool
that exposes the document through the accessibility API and verify that the
decorative image is not exposed through the API.

Expected Results

#1 is true.

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.